Portable ISO Standard Pascal in C, version 3.8
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{$c+}
program factorial;
var r,s : real;
i : integer;
{ TWO VERSIONS OF FACTORIAL: FACT1.P IS FACTORIAL WITH }
{ REAL ARITHMETIC, AND FACT2.P IS FACTORIAL DONE WITH }
{ INTEGERS. AND, READINT.P IS A 'HOME MADE' PROCEDURE )
{ FOR READING IN INTEGERS. }
{ INCLUDE FACT1, FACT2, & READINT: }
{$i+'a:\samples\fact1.p'}
{$i+'a:\samples\fact2.p'}
{$i+'a:\samples\readint.p'}
begin
{ CLEAR THE SCREEN: }
if system('cls') = 0 then ;
{ NOTE THAT, FOR 8086/8087 LIKE ARCHITECTURES, DOING A }
{ SYSTEM CALL MAY AFFECT THE FLOATING-POINT ARITHMETIC }
{ SYSTEM. SO, THE CODE THAT IMPLEMENTS 'system(...)' }
{ INCLUDES A CALL TO RESET THE FLOATING-POINT SYSTEM; }
{ THIS _fpreset() CALL MAY NOT BE NECESSARY FOR OTHER }
{ CHIP OR MAINFRAME COMPUTERS. }
write('Factorial(n); Enter n: ');
readint(Input, i); readln; writeln;
writeln('Value of i from readint: ', i:1, '.');
{ CONVERT FROM INTEGER TO REAL: }
r := i;
{ REAL FACTORIAL: }
s := fact1(r);
writeln('Real factorial of ', trunc(r):1,' is ',
s:1, '.');
{ INTEGER FACTORIAL DOES NOT WORK FOR r > 8: }
i := fact2(trunc(r));
write('Integer factorial of ', trunc(r) : 1, ' is ');
{ 'maxint' IS THE ISO STANDARD PASCAL PREDEFINED CONSTANT: }
if s > maxint then
writeln('greater than maxint = ', maxint:1, '.')
else writeln(i:1, '.');
{ REAL TO INTEGER CONVERSION: }
i := round(s);
writeln('Rounded value of real factorial of ',
trunc(r):1, ' is ', i:1, '.')
{ THIS WILL ALSO WORK (CONSULT YOUR FAVORITE PASCAL }
{ TEXTBOOK FOR DETAILS AND VARIATIONS): }
{ writeln(real_number : WIDTH : PRECISION ); }
end.
